Retraction arrangement for the bow foil of hydrofoil craft

ABSTRACT

A hydrofoil retraction arrangement for water craft having a hull, comprising in combination a bow foil system, composed of a foil and at least one strut placed in front of the stem of the hull. Each strut is fastened to a streamlined bulb-like body protruding beyond the lower stem portion, said body being rotatable transversally through 180* about a rotary axis which is parallel to the longitudinal plane of symmetry of the craft and which forms approximately the bisector of the angle between the stem and the trailing edge of the strut, and the bow having a fixed transition body which leads the lines of the rotatable body into those of the hull.

United States Patent [191 Faber et al.

[ RETRACTION ARRANGEMENT FOR THE BOW FOIL OF HYDROFOIL CRAFT [75] Inventors: Egon Faber; Ernst Jaksch, both of Luzern; Karl-Heinz Stark, Littau, all of Switzerland [73] Assignee: Supramar AG, Luzern, Switzerland [22] Filed: Nov. 13, 1972 [21] Appl. N0.: 306,176

[30] Foreign Application Priority Data Nov. 18, 1971 Switzerland 16799/71 [52] US. Cl. 1l4/66.5 H

[51] Int. Cl B631) l/30 [58] 'Field of Search 1l4/66.5 H

[56] References Cited UNITED STATES PATENTS 3,094,960 6/1963 Lang 114/665 H 3,343,513 9/1967 Bader 114/665 I-I FOREIGN PATENTS OR APPLICATIONS 650,748 10/1962 Canada ll4/66.5 H-

[111 3,804,047 1 Apr. 16, 1974 Primary Examiner-Duane A. Reger Assistant ExaminerBarry L. Kelmachter Attorney, Agent, or FirmWerner W. Kleeman [5 7] ABSTRACT A hydrofoil retraction arrangement for water craft having a hull, comprising in combination a bow foil system, composed of a foil and at least one strut placed in front of the stem of the hull. Each strut is fastened to a streamlined bulb-like body protruding beyond the lower stem portion, said body being rotatable transversally through 180 about a rotary axis which is parallel to the longitudinal plane of symmetry of the craft and which forms approximately the bisector of the angle between the stem and the trailing edge of the strut, and the bow having a fixed transition body which leads the lines of the rotatable body into those of the hull.

4 Claims, 5 Drawing Figures 1 I ll li'lllllllln RETRACTION ARRANGEMENT FOR THE BOW FOIL OF HYDROFOIL CRAFT BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to a' new and improved construction of retractable bow foil system for hydrofoil craft, the strut of which can be rotated about an axis which is parallel to the vertical longitudinal plane of symmetry of the hull.

A primary object of the arrangement of this development is to reduce the large .draught possessed by a hydrofoil in floating condition in order to enable the craft to operate in shallow waters and to land in harbors or at shores with small water depth. Furthermore, the foils can be cleaned in retracted position without lifting the boat.

The retractable bow foil, according to the invention, is in the first instance intended to be used with the canard foil system, wherein the front foil is moved as far as possible to the bow of the ship and carries a smaller portion of the weight than the rear foil. In this extreme forward moved position of the bow foil, the design of the retraction mechanism up to now has caused severe engineering difficulties. In the heretofore known arrangements the foil is swung upwardly about a lateral axis in the travel or driving direction. Consequently, the pivot or swivel axis, to which the strut is attached, is placed behind the stem at a spot with sufficient width to assure an adequate base for the bearings. This implies that the bow or prow must be provided with 'a door or hatch which has to be opened before the foil can be swung upwardly. The disadvantages of this arrangement are obvious. Besides the retracting mechanism there is also required an opening mechanism for the movable parts of the prow and the design of the forepart, which according to the rules of ship construction should be solid and strong, becomes complicated, weak and vulnerable. In the hullborne mode and with retracted foils.- the prow is opened and filled with water to the collision bulkhead. Furthermore the arrangement permits only the use of foils with a single center strut.

The invention avoids the drawbacks of the known retraction arrangements by placing the retractable bow foil in front of the stem of the boat. Its strut or struts are fastened to a streamlined body protruding from the lower stem portion. which body is rotatable through 180 transversely with respect to the line of advance or travel about an axis which forms approximately the bisector of the angle between the 'stem and the trailing edge(s) of the strut(s). To the prow is fixed a transition-body which leads the lines of the rotatable streamlined body into those of the hull.

The simplicity of this arrangement cannot be exceeded. The prow can be constructed in the usual way, sturdy and resistant. The streamlines and the influx of water to the hull can be adapted ,to the low drag configurations and they remain unchanged in the operational position of the foil as well as in the retracted position. Any strut arrangement and number is practicable.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein:

FIG. 1 illustrates the retraction arrangement in side view with one strut, whereby the hull is shown in sectional view;

FIG. 2 illustrates the retraction arrangement according to FIG. 1 in exterior side view;

FIG. 3 is a sectional side view of the arrangement with a strut pivotably mounted in the streamlined body;

FIG. 4 shows the arrangement in front view whereby the foil is provided with three struts; and

FIG. shows the retraction mechanism in front view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is shown in section a hydrofoil l which can possess a fully submerged or partially submergedconfiguration. In this embodiment it is connected by a single strut 2 with the streamlined body 3, which protrudes beyond the stem 4 in the manner of a bulb bow. The foil 1 with its strut 2 is placed in front of the stem 4 of the hull 5. The streamlined body 3 is provided with the shaft 6 which is pivoted in the bearings 7 and 8. The axial center line of the body 3 approximately bisects the angle a between the leading edge of the stem and the trailing edge of the strut. Consequently, the trailing edge of the strut 2 is disposed parallel to said leading edge when the foil is swung upward through The rotatable streamlined body 3 is preferably positioned at the lower part of the stem 4 in such a way that its lower edgeis in line with the lower keel edge. This low position offers the advantage that the strut can possess the lowest possible length, which is desirable for stress reasons, and that the retracted foil assumes the lowest possible height over the deck. At the bow or prow there is provided the fixed transition body 9 which, as can be seen from FIG. 2, leads or merges the lines of the streamlined body 3 into the hull 5 such that an attachment or contact of the flow is ensured at the transition location from the body 3 to the hull 5.

As illustrated, in the preferred embodiment of the invention the stem 4 of the hull 5 is forwardly inclined in known manner such that the strut 2 is rearwardly inclined'in the lower position of operationfThis affords the advantage that the spray generated at the piercing point of the strut through the surface of the water is reduced, by which not only the drag of the strut is re-' duced, but above all there is avoided that the spray will impinge against the hull causing an additional drag.

The strut 2 or several struts respectively can be used for the directional control of the boat. For this purpose the struts can be provided with a flap or rudder surface 10 (FIG. 1) which, when deflected, produces a side force in known manner. According to another embodiment the strut, rigidly connected to the foil, can be rotatable as a unit about a verticalaxis as shown in FIG. 3. In this case the strut has a shaft 11 defining an axis of rotation and which is pivoted in the bearings 12 and 13 of the streamlined body 3. The axis of rotation defined by the shaft 11 is placed as much as possible at the center of the strut where the greatest thickness is available and the direction of the axis extends parallel to the strut axis, or else is. inclined towards the front in the direction of the lower struts leading edge in order to attain better balancing of the rudder, the center of pressure of which is placed in front of the center line.

Balancing can also be effected by placing the foil at the rear part of the strut inversely from the position depicted in FIG. 1.

FIG. 4 shows the retraction arrangement for a surface piercing foil 1 which, in this embodiment, possesses three struts 2. The struts 2 are all fixed to the streamlined body 3 if a rigid connection with said body is required. If, however, turning or pivoting ability of the complete foil system is desired, then all three struts 2 joint the shaft 11 defining the pivot axis in the line of symmetry, as illustrated in FIG. 4. This shaft is pivoted in the streamlined body 3 in the same way as shown in FIG. 3.

FIG. 5 discloses the retraction mechanism with the aid of which rotation of the foil through 180 is obtained by the piston stroke of a single actuator. It includes a triangular body 14, one leg of which, positioned near the shaft 6 defining the rotary axis of the foil system, is pivoted by pivot means a at a hull portion in the axis 15. The other leg of the triangular body 14 is connected bya rod 16 with a lever 17 of the shaft 6. At the third leg acts the piston rod of the hydraulic cylinder 18. From FIG. 5 there can be seen the manner in which the angle of about 125, which the point of application of the piston rod 18a describes, is transferred to an angle of pivoting of 180 of the shaft 6 with the aid of the triangular body 14.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

l. A hydrofoil retraction arrangement for water craft having a hull provided with a stem and a prow comprising, in combination, a bow foil system composed of a foil and at least one strut placed in front of the stem of the hull, the strut having a trailing edge and being fastened to a streamlined bulb-like body having contour lines and protruding beyond the lower stem portion,

means mounting said streamlined body to be rotatable transversely with respect to the direction of travel of the craft through an angle of about about an axis of rotation which is parallel to the longitudinal plane of symmetry of the craft and which forms approximately the bisector of the angle between the stem and said trailing edge of the strut, and the prow of the hull having a fixed transition body which leads the contour lines of said rotatable body into those of the hull.

2. A hydrofoil retraction arrangement for water craft as defined in claim 1, wherein the stem of the hull is forwardly inclined and the trailing edge of the strut is placed parallel to the stem in its retracted upper position, so that the strut is inclined rearwardly in its lower position of operation.

3. A hydrofoil retraction arrangement for water craft as defined in claim 2, wherein the strut is provided with means defnining a pivot axis extending approximately parallel to the strut axis, means for pivotably mounting said pivot axis-defining means at the rotatable streamlined body such that the strut can be turned about said pivot axis for the directional control of the craft.

4. A hydrofoil retraction arrangement as defined in claim 3, further including a shaft defining the axis of rotation of the rotatable streamlined body, a retraction mechanism for the rotatable streamlined body incorporating a triangular body having three legs, means for pivotably mounting one leg positioned near the axis of rotation of the streamlined body at a hull portion, a lever provided for said shaft, another leg of said triangular body being connected by a rod with said lever, and

i an actuator means connected with the third leg of said triangular body. 

1. A hydrofoil retraction arrangement for water craft having a hull provided with a stem and a prow comprising, in combination, a bow foil system composed of a foil and at least one strut placed in front of the stem of the hull, the strut having a trailing edge and being fastened to a streamlined bulb-like body having contour lines and protruding beyond the lower stem portion, means mounting said streamlined body to be rotatable transversely with respect to the direction of travel of the craft through an angle of about 180* about an axis of rotation which is parallel to the longitudinal plane of symmetry of the craft and which forms approximately the bisector of the angle between the stem and said trailing edge of the strut, and the prow of the hull having a fixed transition body which leads the contour lines of said rotatable body into those of the hull.
 2. A hydrofoil retraction arrangement for water craft as defined in claim 1, wherein the stem of the hull is forwardly inclined and the trailing edge of the strut is placed parallel to the stem in its retracted upper position, so that the strut is inclined rearwardly in its lower position of operation.
 3. A hydrofoil retraction arrangement for water craft as defined in claim 2, wherein the strut is provided with means defnining a pivot axis extending approximately parallel to the strut axis, means for pivotably mounting said pivot axis-defining means at the rotatable streamlined body such that the strut can be turned about said pivot axis for the directional control of the craft.
 4. A hydrofoil retraction arrangement as defined in claim 3, further including a shaft defining the axis of rotation of the rotatable streamlined body, a retraction mechanism for the rotatable streamlined body incorporating a triangular body having three legs, means for pivotably mounting one leg positioned near the axis of rotation of the streamlined body at a hull portion, a lever provided for said shaft, another leg of said triangular body being connected by a rod with said lever, and an actuator means connected with the third leg of said triangular body. 